Game breaking campaign glitch help

I’m trying to beat the game in legendary so I can chiefs armor. I got to the level reclaimer but now whenever I get to the part where the lich is, it doesn’t lower it’s gravity lift. I spent at least an hour trying to revert and restart and tying again and it’s still glitched. Does anyone know how to fix this?

bump

It should be floating next to a rock you can jetpack on to and then from there jetpack into the lich

Try going to the top of the hill where the lich is and get a checkpoint. Then just try and take out everything that comes out like the wraith and ghosts. It took me a while as well before the damn gravity lift finally shot down.